Problems relating to the shelf stability of enzyme-containing preparations, for example of enzyme preparations or of washing or cleaning agents or disinfectants, are known from the prior art. This problem is especially acute with liquid enzyme preparations or liquid enzyme-containing surfactant preparations, for example liquid washing or cleaning agents. After only a short time they lose a significant degree of enzymatic, in particular hydrolytic, and especially proteolytic activity. The surfactant preparation, for example the washing or cleaning agent or disinfectant, then no longer exhibits optimum cleaning performance. One objective in the development of enzyme-containing surfactant preparations is therefore to stabilize the contained enzymes and to protect them from denaturing and/or cleavage and/or degradation, in particular during storage and/or during utilization of the preparation. Hydrolytic enzymes in particular, and especially proteases, but for example also amylases, are of interest in this regard. For this, chemical compounds that in particular reversibly inhibit proteases, can be added to the preparations and thereby act all in all as stabilizers for the proteases and other comprised enzymes. The inhibitors have to be reversible in this case, as the enzyme activity should only be temporarily prevented, in particular during storage, but no longer during the cleaning process.
Boric acid and boric acid derivatives, even at a comparatively low concentration, occupy a prominent position among the enzyme stabilizers that are effective in surfactant preparations. International patent application WO 96/21716 A1, for example, discloses that boric acid derivatives and boronic acid derivatives acting as protease inhibitors are suitable for stabilizing enzymes in liquid preparations, among them washing and cleaning agents. A selection of boronic acid derivatives as stabilizers is disclosed, for example, in the international patent application WO 96/41859 A1. Meta- and/or para-substituted phenylboronic acids are presented as enzyme stabilizers in WO 92/19707 A1 and EP 478050 A1. Complexes of boric acids and boric acid derivatives with aromatic compounds are disclosed in EP 511456 A1 as enzyme stabilizers in liquid detergent compositions.
Boric acids and boric acid derivatives have the disadvantage, however, that they form undesired secondary products with other ingredients of a surfactant preparation, in particular the ingredients of washing or cleaning agents or disinfectants, such that they are no longer available in the relevant agents for the desired cleaning purpose, or in fact remain behind, for example on the washed item, as a contaminant. In addition, boric acids and borates are increasingly considered to be disadvantageous in environmental terms.
Indeed, boric acid-free or boron-free compounds are known from the prior art to reversibly inhibit hydrolytic enzymes and thus stabilize them. However, they frequently have the disadvantage that they do not adequately stabilize the enzymes in a preparation of the enzyme, in particular not in liquid surfactant preparations such as for example in washing or cleaning agents or disinfectants. In order to bring about a satisfactory stabilization, such compounds would frequently have to be employed in such a great amount, thereby making their use impossible, as these amounts cannot be satisfactorily incorporated into the enzyme preparation and/or their incorporation becomes economically unviable.
The underlying object of the present invention is to adapt a hydrolytic enzyme to a component that stabilizes the hydrolytic enzyme, in particular a reversible inhibitor, and consequently to improve its stabilization by these components.
The component that stabilizes the enzyme should preferably contain as little as possible boric acid or boron-containing compounds or preferably, should be free of boric acid and/or boron.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.